1. Field of the Invention
The present invention relates to a digital image input device for a copying machine, a facsimile, or an electronic file and, more particularly, to a compact, manual image reader.
2. Description of the Prior Art
Digital image reading (detecting) devices have been proposed such as a device which uses a reducing optical system and a CCD, or a contact-type line sensor comprising an optical sensor array which is brought into contact with an original for reading an image thereon. When a contact-type line sensor is used, the space conventionally required for the optical system can be reduced, so that the overall reading device can be rendered light in weight and compact in size.
Although a manual reader using such a contact-type line sensor is plausible, manual scanning results in an irregular scanning speed, making correct scanning difficult, and a circuit configuration for synchronizing line scanning is complex.
Turn on control of a light source for image reading is cumbersome while constant powering of the light source results in a high power consumption.
When high-speed scanning is performed with a manual image reader, processing of read image signals cannot follow high-speed scanning, resulting in a disturbed image.
When a reading sensor is moved on an original for image reading, the original position is deviated, and the image signal may become skipped or overlapped.